This invention relates to dental apparatus and more particularly to a mounting plate assembly used for mounting dental casts onto a dental articulator to simulate jaw movement. With such an instrument, the movement of a person's jaws and the interaction of the upper and lower teeth may be studied.
Dental casts representing the jaw, gum, and teeth are generally mounted on the articulator using a removable dental cast mounting plate and a putty-like mounting plaster that hardens as it dries. The plate generally includes protruding structure having an undercut portion so the mounting plaster fills in beneath this portion. When the plaster hardens, the plaster beneath the undercut effectively prevents the dental cast from separating from the mounting plate. One common form of such protruding structure is a knob having an enlarged head. The mounting plate is removably attached to the frame of the articulator by a mounting screw.
A dentist may use a particular dental cast many times over a period of several months. For each of these uses, the cast, with its mounting plate, is attached to the dental articulator. Thus, the mounting plate must be durable enough to withstand repeated mounting and remounting. These mounting plates are typically manufactured of metal for maximum accuracy and durability.
When the dentist is finished with a particular cast, he may wish to remove the dental cast from the mounting plate, so the mounting plate can be reused rather than disposing of the mounting plate along with the cast. However, the knob or other structure protruding from the surface of the mounting plate to hold the cast onto the plate makes removal of the cast difficult. The dried, hardened mounting material beneath the enlarged head of the knob must be carefully scraped away before a new cast is mounted. This cleaning takes considerable time and effort and is often performed by a dentist or a highly paid assistant.
To reduce the cost associated with disposing of the mounting plate with the cast, plastic mounting plates have been used which cost substantially less than metal mounting plates. However, plastic mounting plates are both less accurate than the metal mounting plates, and are not as durable for those castings that may be repeatedly used over an extended period of time. The lack of accuracy with the plastic mounting plates causes mountings made to be not perfectly repeatable, which affects the usefulness of the castings. Also, the expense of the plastic mounting plates is still too high to be practically disposable in that an active practitioner may use hundreds or thousands of casts over a period of time.
Thus, a need exists for an accurate mounting plate system that allows multiple casts to be mounted at a minimum cost.